Method for simulating temperature proportions in asphalt mixture transportation process

Abstract

The invention discloses a method for simulating each temperature proportion in an asphalt mixture transportation process, which comprises the following steps of: firstly, modeling three parts, namely an asphalt mixture transportation vehicle, a stacking form in the asphalt mixture vehicle and tarpaulin for covering an asphalt mixture through three-dimensional modeling software, then importing the model into thermal analysis software, and carrying out steady-state thermal analysis to obtain the temperature proportion of each temperature proportion in the asphalt mixture transportation process. The initial stable state of the system in the natural environment is simulated, and transient thermal analysis is used to simulate the whole process of heat from the initial stable state to a loss state in the natural environment. And finally obtaining the proportion of the asphalt mixture in each temperature range at different time points. According to the method, the temperature change and the specific proportion of the asphalt mixture in each area in the whole transportation process can be accurately reflected, the defect that the temperature of each part of the whole asphalt mixture is difficult to measure in a field test is overcome, and an important theoretical basis is provided for optimizing the transportation of the asphalt mixture from the perspective of temperature segregation.

Description

Technical Field

[0001] The invention belongs to the technical field of road engineering, and in particular relates to a method for simulating temperature proportions during asphalt mixture transportation. Background Art

[0002] Asphalt mixture is one of the most important materials widely used in road construction and maintenance. The quality and performance of roads will be affected by the quality of asphalt mixture. Temperature control is crucial to the quality assurance of asphalt mixture. During transportation, especially in long-distance transportation, the temperature of asphalt mixture may drop significantly due to the extension of time and changes in external environmental conditions. The drop in the temperature of asphalt mixture will directly lead to segregation of the mixture, which in turn affects the quality of the road surface. At present, the research on segregation of asphalt mixture is mostly focused on the paving and compaction stages, while there is less research on segregation caused by temperature changes in the transportation stage, and there is also less monitoring of temperature during transportation. Summary of the invention

[0003] The purpose of the present invention is to make up for the shortcomings of the current temperature monitoring method for asphalt mixture transportation, and to propose a method for estimating the proportion of various temperatures in the asphalt mixture transportation process based on the finite element analysis node extraction method.

[0004] The present invention adopts the following technical solution:

[0005] Step 1: Use 3D modeling software to build a 3D model of the asphalt mixture transport vehicle, a 3D model of the asphalt mixture stacking inside the vehicle, and a model of the tarpaulin used to cover the asphalt mixture;

[0006] Step 2: Import the constructed model into the thermal analysis software and set the parameters of the asphalt mixture transport carriage, asphalt mixture and tarpaulin engineering materials;

[0007] Step 3: Select appropriate meshing method and mesh size to mesh the asphalt mixture and the transport compartment, with the number of meshes being M and the number of nodes being N;

[0008] Step 4: Connect the steady-state thermal analysis system, set the initial temperature of the environment, insert the temperature module, set the temperature of the asphalt mixture transport compartment and the asphalt mixture storage temperature in the vehicle, and solve to obtain the steady-state thermal system temperature;

[0009] Step 5: Connect the transient thermal analysis system, set the simulated temperature range and time step size, and solve the temperature change cloud diagram of the entire assembly model under the temperature range and time step size conditions;

[0010] Step 6: Solve the above thermal simulation results, insert the temperature calibration of the initial state obtained in step 4 and the process temperature change results obtained in step 5, export the text file of the temperature of each node in the asphalt mixture simulation part at H time points, and obtain the node number, x, y, z coordinates and temperature of each node divided at H time points, and the node temperature data;

[0011] Step 7: Import the node temperature data into the table and calculate the node ratio of each temperature zone:

[0012] =(COUNTIF(E:E,">F")-COUNTIF(E:E,">G")) / N

[0013] Calculate the ratio of nodes whose temperature is greater than the temperature parameter F and less than or equal to the temperature parameter G

[0014] =(COUNTIF(E:E,">E")-COUNTIF(E:E,">F")) / N

[0015] Calculate the ratio of nodes whose temperature is greater than temperature parameter E and less than or equal to temperature parameter F

[0016] =(COUNTIF(E:E,">D")-COUNTIF(E:E,">E")) / N

[0017] Calculate the ratio of nodes whose temperature is greater than temperature parameter D and less than or equal to temperature parameter E

[0018] =(COUNTIF(E:E,">C")-COUNTIF(E:E,">D")) / N

[0019] Calculate the ratio of nodes whose temperature is greater than temperature parameter C and less than or equal to temperature parameter D

[0020] =(COUNTIF(E:E,">B")-COUNTIF(E:E,">C")) / N

[0021] Calculate the ratio of nodes whose temperature is greater than temperature parameter B and less than or equal to temperature parameter C

[0022] =(COUNTIF(E:E,">A")-COUNTIF(E:E,">B")) / N

[0023] Calculate the ratio of nodes whose temperature is greater than temperature parameter A and less than or equal to temperature parameter B

[0024] =COUNTIF(E:E,"<=A") / N

[0025] Calculate the ratio of nodes whose temperature is less than or equal to temperature parameter A.

[0026] Beneficial effects:

[0027] 1. The method proposed in the present invention for simulating the ratio of various temperatures during asphalt mixture transportation based on the node extraction method can use a computer to simulate the temperature changes in various regions during asphalt mixture transportation, as well as the ratio of asphalt mixture in different temperature ranges, which makes up for the deficiency that it is difficult to determine the temperature of each part of the entire asphalt mixture in field tests, and provides an important theoretical basis for optimizing the safety and reliability of asphalt mixture transportation from the perspective of temperature segregation.

[0028] 2. It is used to formulate the evaluation index of temperature segregation during the transportation of asphalt mixture, and to quantitatively evaluate the temperature segregation during the transportation of asphalt mixture. In actual transportation, simulation analysis is carried out before transportation, and the simulation results show the time point at which the temperature in some areas will be too low and there will be a risk of segregation, so that the transport tank truck will start heating when it arrives at this time point. This reduces the heating cost compared to the method of heating throughout the whole process to avoid asphalt segregation.

[0029] 3. The proportion of asphalt mixture in different temperature ranges is calculated by analogy by dividing the number of nodes in different temperature ranges by the total number of nodes. Since the model is sufficiently sophisticated and the number of nodes is large enough, the error can be ignored in actual engineering.

[0030] 4. The present invention requires relatively low equipment, funds and time. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The three-dimensional modeling software assembly model used in the present invention;

[0032] Figure 2 A grid division diagram used in the present invention;

[0033] Figure 3 It is a temperature change cloud diagram of transient thermal simulation adopted by the present invention;

[0034] Figure 4 A temperature distribution diagram of a carriage model of an embodiment;

[0035] Figure 5 Statistical result diagram of temperature distribution of the embodiment;

[0036] Figure 6 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0037] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. The embodiments are implemented based on the technical solution of the present invention. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0038] DETAILED DESCRIPTION Figure 1 In the embodiment, the volume of asphalt is the defined container volume.

[0039] The three-dimensional modeling software described in the present invention can be software with legal copyright, such as SolidWorks, ANSYS Workbench, etc.

[0040] The present invention discloses a method for simulating the temperature ratios during asphalt mixture transportation based on an extraction node method, comprising the following steps:

[0041] Step 1: Use 3D modeling software to build a 3D model of the asphalt mixture transport truck, a 3D model of the asphalt mixture stacking inside the truck, and a model of the tarpaulin used to cover the asphalt mixture. The 3D model of the asphalt mixture transport truck, the asphalt mixture stacking inside the truck, and the tarpaulin used to cover the asphalt mixture are combined into an assembly as three parts. The truck compartment is 6.4m long, 2.6m wide, and 1.7m high, and is made of 0.02m thick steel plate.

[0042] Step 2: Import the constructed model into the thermal analysis software and set the parameters of the asphalt mixture transport carriage, asphalt mixture and tarpaulin engineering materials. As a preferred embodiment of the present invention, the thermodynamic parameters of the selected materials are:

[0043]

[0044]

[0045] Table 1. Material optimization parameters

[0046] Step 3: Select appropriate meshing method and mesh size to mesh the asphalt mixture and transport compartment. The mesh size is 50 mm, the number of meshes is 326615, and the number of nodes is 1107718. The meshing results are as follows: Figure 2 shown.

[0047] Step 4: Connect the steady-state thermal analysis system, set the initial ambient temperature to 25°C, insert the temperature module, set the asphalt mixture transport compartment temperature and the asphalt mixture storage compartment temperature, and solve for the steady-state thermal system temperature.

[0048] Step 5: Connect the transient thermal analysis system, set the initial ambient temperature to 25°C, set the number of steps to 12, the time step to 60s, and the time range to 0-7200s. Insert the convection module, set the thermal radiation emissivity to 0.9, and calculate the convection coefficient according to the following formula:

[0049]

[0050] Where A is the area of ​​the carriage surface or tarpaulin surface, of which the top and bottom A is 16.64m 2 , the side A on both sides is 10.88m 2 , front and rear side A is 4.42m 2 , Q is the heat transfer per unit time on area A, Q is about 2000W when there is a tarpaulin, and about 10000W when there is no tarpaulin, t w The temperature of the car body or tarpaulin surface is 80℃, t ∞ The external ambient air fluid temperature is 25°C.

[0051] The calculated convection coefficient on both sides of the asphalt mixture transport compartment is 16.71 W / m 2 ℃, the convection coefficient of the front and rear sides is 41.13W / m 2 ℃, the convection coefficient of the top surface (with tarpaulin) is 2.18W / m 2 ℃, bottom convection coefficient is 10.92W / m 2 ·℃, and thus the temperature change cloud diagram of the entire assembly model within the time step range is obtained, such as Figure 3 The temperature distribution diagram of the entire carriage at the time node t=7200s is shown. The temperature displayed in the figure is color-coded from 32.873℃ to 170℃. It can be seen that the asphalt temperature in the carriage is between 109-139℃, and the temperature at the edge of the transport carriage that does not touch the asphalt mixture is as low as 48℃, which means that the heating function of the transport vehicle must be turned on at this time point, otherwise there is a risk of asphalt segregation at the edge.

[0052] Step 6: Solve the above thermal simulation results, insert the initial temperature calibration obtained in step 4 and the process temperature change results obtained in step 5. Because the total time is 7200s and the step time is 60s, that is, export the text file of the temperature of each node in the asphalt mixture simulation part at 120 time points, and obtain the node number, x, y, z coordinates and temperature of each node divided at these 120 time points. The node temperature data is in the cell of column E by default.

[0053] Step 7: Import the node temperature data into the table and calculate the node ratio of each temperature zone:

[0054] =(COUNTIF(E:E,">F")-COUNTIF(E:E,">G")) / N

[0055] Calculate the ratio of nodes whose temperature is greater than the temperature parameter F and less than or equal to the temperature parameter G

[0056] =(COUNTIF(E:E,">E")-COUNTIF(E:E,">F")) / N

[0057] Calculate the ratio of nodes whose temperature is greater than temperature parameter E and less than or equal to temperature parameter F

[0058] =(COUNTIF(E:E,">D")-COUNTIF(E:E,">E")) / N

[0059] Calculate the ratio of nodes whose temperature is greater than temperature parameter D and less than or equal to temperature parameter E

[0060] =(COUNTIF(E:E,">C")-COUNTIF(E:E,">D")) / N

[0061] Calculate the ratio of nodes whose temperature is greater than temperature parameter C and less than or equal to temperature parameter D

[0062] =(COUNTIF(E:E,">B")-COUNTIF(E:E,">C")) / N

[0063] Calculate the ratio of nodes whose temperature is greater than temperature parameter B and less than or equal to temperature parameter C

[0064] =(COUNTIF(E:E,">A")-COUNTIF(E:E,">B")) / N

[0065] Calculate the ratio of nodes whose temperature is greater than temperature parameter A and less than or equal to temperature parameter B

[0066] =COUNTIF(E:E,"<=A") / N

[0067] Calculate the ratio of nodes whose temperature is less than or equal to temperature parameter A.

[0068] Where A = 130 °C, B = 140 °C, C = 150 °C, D = 160 °C, E = 170, F = 180 °C, G = 190 °C, N is the total number of nodes 1107718, and the resulting temperature range is shown in the figure below: Figure 4 and Figure 5 shown.

[0069] Figure 4 This is the temperature cross-section diagram of the carriage at the time point t=7200s. The temperature displayed in the figure is in the range of 38.279℃ to 170℃ according to the color marking. It can be seen that the temperature in the middle red area is as high as 170℃, and the edge temperature decreases to 82.168℃, which is far below the segregation temperature. By setting the time t to be less than 7200s, the time node t1 when the regional temperature just drops to the segregation temperature can be found. This time t1 can be used to guide the time when the asphalt tanker starts heating in actual transportation;

[0070] Figure 5In the figure, the horizontal axis is time and the vertical axis is the percentage of temperature. By combining the information in the figure, we can know the percentage of each temperature of the asphalt at any time point, which can be used to determine from which time point a sufficient percentage of the asphalt temperature is not high enough to start heating. For example, if the actual engineering standard is that no more than 10% of the asphalt can be below 150℃, otherwise the loss of segregation will be too great, then according to Figure 5 It can be seen that the time point t=1200s is the critical time when the proportion of asphalt below 150℃ begins to exceed 10%, and heating must be started at this time.

[0071] The present invention provides a method for simulating the temperature ratios during asphalt mixture transportation. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be considered as the protection scope of the present invention. All components not specified in this embodiment can be implemented using existing technologies.

Claims

1. A method for simulating the temperature ratios during asphalt mixture transportation, characterized in that: The steps include: Step 1: Use 3D modeling software to build a 3D model of the asphalt mixture transport vehicle, a 3D model of the asphalt mixture stacking inside the vehicle, and a model of the tarpaulin used to cover the asphalt mixture; Step 2: Import the constructed model into the thermal analysis software and set the parameters of the asphalt mixture transport carriage, asphalt mixture and tarpaulin engineering materials; Step 3: Grid the asphalt mixture and the transport compartment, with the number of grids being M and the number of nodes being N; Step 4: Steady-state thermal analysis: Set the initial temperature of the environment, insert the temperature module, set the temperature of the asphalt mixture transport compartment and the asphalt mixture storage temperature in the vehicle, and solve to obtain the steady-state thermal system temperature; Step 5: Transient thermal analysis: Set the simulated temperature range and time step size, and solve to obtain the temperature change cloud diagram of the entire assembly model under the conditions of the temperature range and time step size; Step 6: Solve the above thermal simulation results, combine the temperature calibration of the initial state obtained in step 4 and the process temperature change results obtained in step 5, and derive the temperature result data of each node of the asphalt mixture simulation part at H time points, and obtain the node number, x, y, z coordinates and temperature of each node divided at H time points, and the node temperature data; Step 7: Import the node temperature data into the table and calculate the node proportion in each temperature zone.

2. The method for simulating the temperature ratios during asphalt mixture transportation according to claim 1, characterized in that: The material of the three-dimensional model of the carriage of the asphalt mixture transport vehicle described in step 1 is steel plate.

3. The method for simulating the temperature ratios during asphalt mixture transportation according to claim 1, characterized in that: The thermodynamic parameters of the material selected in step 2 include density, thermal conductivity and specific heat capacity.

4. The method for simulating the temperature ratios during asphalt mixture transportation according to claim 1, characterized in that: The grid division size described in step 3 is a square with a side length of less than 0.1 meter.

5. The method for simulating the temperature ratios during asphalt mixture transportation according to claim 1, characterized in that: The convection coefficient h of each side in step 5 is calculated as follows: Where A is the area of ​​the car body or tarpaulin, Q is the heat transfer per unit time on area A, t w is the temperature of the car body or tarpaulin surface, t ∞ is the external ambient air fluid temperature.

6. According to the method for simulating the ratio of various temperatures during the transportation of asphalt mixtures according to claim 1, in step 7, the ratio of the number of nodes in a specific temperature range is calculated by the following formula to cover the temperature range that may be reached during the transportation of asphalt mixtures: =(COUNTIF(E:E,">F1")-COUNTIF(E:E,">F2")) / N Calculate the ratio of nodes whose temperature is greater than temperature parameter F1 and less than or equal to temperature parameter F2, where N is the total number of nodes.

7. According to the method for simulating the temperature ratios during asphalt mixture transportation according to claim 1, the range of each temperature parameter in step 7 is greater than 0 degrees Celsius and less than 190 degrees Celsius.

8. According to the method for simulating the temperature ratios during asphalt mixture transportation according to claim 1, in step 2, the three-dimensional model of the asphalt mixture transportation vehicle, the asphalt mixture stacking model inside the vehicle, and the covering tarpaulin are combined as three parts into an assembly.

9. According to the method for simulating the temperature ratios during asphalt mixture transportation according to claim 1, in step 5, the initial temperature of the environment, the number of steps and the time step are set; a convection module is inserted to set the convection coefficients of the five sides of the asphalt mixture transportation compartment except the top tarpaulin, set the convection coefficient of the top tarpaulin, and set the thermal radiation emissivity.

10. The method for simulating the temperature ratios during asphalt mixture transportation according to claim 1, characterized in that: The convection coefficient of the top tarpaulin is smaller than that of the other five surfaces, only one-fifth of that of the other five surfaces.

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